VOC's (volatile organic compounds) are widely used as propellants in aerosol spray products such as hair sprays, deodorants, and the like. Some environmentalists believe that VOC's have an adverse effect on the ozone layer of the earth's atmosphere. Thus, environmental lobbies in various states are working toward enacting legislation which reduces or eliminates the use of VOC's in personal care products marketed in the aerosol spray form. Legislation has been enacted in certain states which limits the amount of VOC's in an aerosol product to 80%. It is anticipated that by 1996 only 55% VOC's will be permitted in aerosol spray products.
Aerosol hair sprays are ubiquitous in our society, and are usually anhydrous compositions which contain hair fixative resins in conjunction with a volatile propellant or VOC. The propellant enables the resin to be applied to the hair in a fine dispersed spray which exhibits hair holding power.
If VOC's are reduced or removed from hair sprays, other nonvolatile constituents must be substituted in place of the VOC. There are few nonvolatile liquids which would be suitable, and of those, water is preferred for economic and safety reasons.
However, eliminating or reducing VOC's in anhydrous systems, or moving into low VOC content aqueous based systems involves significantly changing formulation constituents. For example, if VOC's are reduced in the traditional anhydrous systems, they must be replaced with some suitable non-VOC ingredient. If that ingredient is water, the result is an aqueous based system and the traditional water insoluble resins must be replaced with water soluble resins. However, it has been found that hair sprays comprised of water soluble resins in an aqueous system are commercially unsatisfactory because these compositions cause hair to droop and become tacky under high humidity, and they prolong the drying time of the hair. In addition, the water beads which accumulate on hair are too large due to increased surface tension. These systems are also difficult to use with aerosol containers, often clogging the spray nozzle or causing system malfunction.
There is thus a need for hairsprays which contain less than 80% VOC's and yet provide an aesthetically pleasing commercial product.